GtkRadiant is a level design program developed by id Software and Loki Software. It is used to create maps for a number of computer games. GtkRadiant originated as Q3Radiant, the Quake III Arena level design tool, which was a Windows-only application. Two major things are different in GtkRadiant: it is based on the GTK+ toolkit, so it also works in Linux and Mac OS X, and it's also game engine-independent, with functionality for new games added as game packs. GtkRadiant is an Open Source application. Source code is publicly available from id Software's Subversion repository and new additions to the code are covered under open source licenses. The core Q3Radiant code, however, was originally under id Software's proprietary license. The license for both the editor and toolset (notably Q3Map2, the BSP compiler) was changed in February 2006, and publicly released under the GPL on February 17. More up-to-date fork, NetRadiant, is available as `games/netradiant' port. WWW: http://www.qeradiant.com/